We have designed and constructed a robust and inexpensive high voltage pulsing system for carrying out delayed-extraction MALDI time-of-flight MS measurements. We have used this system to run both of our linear time-of-flight instruments either in continuous-extraction (CE) or delayed-extraction (DE) modes. Comparison of UV- and IR-MALDI using CE and DE has led to a number of interesting discoveries.. Thus, for example, we have found that IR-MALDI produces demonstrably cooler protein ions than UV-MALDI and that the tails on both IR- and UV-MALDI spectra originate from multiple association of Na cations with the protein. The results have been reported W. Zhang, S. Niu, B.T. Chait "Exploring Infrared Wavelength Matrix-Assisted Laser Desorption/Ionization of Proteins with Delayed Time-of-Flight Mass Spectrometry" J. Am. Soc. Mass Spectrom. 9 (1988) 879-884.